Cutting machinery such as gear shaping machines are used to create gear teeth along the outer or inner periphery surface of gear members. As will be readily be appreciated, gears come in a wide variety of shapes and sizes, with different shapes and sizes of teeth being provided along a gear surface. Additionally, some gears will have straight gear teeth and flutes therebetween which are parallel with the rotational axis of the gear while other gears will have helical or slanted gear teeth and flutes therebetween relative to the rotational axis of the gear. Additionally, some gears will be crowned in that one or both sides of the gear will be rounded as the gear teeth and flutes approach one or both side edges of the gear.
A common approach to providing machinery for shaping gears in disclosed in Tlaker et al., U.S. Pat. No. 4,125,056, the entire disclosure of which is hereby incorporated by reference. As disclosed therein, a machine includes a hydraulically operated reciprocating spindle which drives a vertical cutter for shaping a gear. The spindle comprises a piston which is slidable in a cylinder. The spindle piston is a differential piston in that it has two faces of different area to which hydraulic fluid under pressure is controllably directed. The larger area piston face is used to drive the spindle downwardly in the cutting stroke and the smaller area piston face is used to drive the spindle upwardly in the return stroke. Further, the spindle piston has an axial bore which receives a vertically reciprocating valve. The valve is reciprocated in a manner which causes a spindle to move downwardly at a controlled lower velocity and moved upwardly on the return stroke at a much higher velocity to provide a greater overall production efficiency. The way in which the machinery is driven is through mechanical cam and inversely related lever/linkage mechanisms which require complex spring housings, mechanical linkages and adjustment mechanisms.
In a machine such as Tlaker et al., the spindle is carried for linear reciprocation within a saddle that is pivotably connected to a main frame. During the downward cutting stroke, the spindle is kept in a true vertical orientation to facilitate cutting action between the cutter and the workpiece. However, the saddle (in which the spindle linearly reciprocates) is pivotably mounted as such and during the return stroke, the saddle and spindle are pivoted slightly to a slightly offset vertical orientation by virtue of mechanical cam action to relieve the cutter from the cutting surface and thereby allow the spindle and cutter to retract free and clear of the workpiece.
As it relates to the general state-of-the-art, additional reference can be had to U.S. Pat. Nos. 3,628,359; 4,136,302; 4,254,690; 4,533,858; 4,542,638; 4,629,377; 4,784,538; and 5,345,390, the entire disclosures of which are also hereby incorporated by reference in their entireties. Additional reference can be had to U.S. Pat. No. 3,741,659.
Machinery of the type disclosed in Tlaker et al. have been commercially sold under the trademark HYDROSTROKE® and have met with substantial commercial success. With that being said, the relevant art has largely remained relatively stagnant from a mechanical cam timing, control, and hydraulic operation standpoint. As will be readily appreciated once the present invention is understood, there are several deficiencies heretofore that have not been realized in such gear shaping machines which are hereby improved upon with the present invention.